It’s been 18 years since Pluto’s celestial status was called into question—yet the matter seems far from settled. We asked experts from both sides to make their case. This 2015 NASA image of Pluto ...

(CNN) — Jupiter’s moon Ganymede may have shifted on its axis when a massive asteroid smashed into it about 4 billion years ago, according to a new study. Ganymede, the largest moon in the solar system ...